/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.support.v4.util;

import java.io.PrintWriter;

/**
 * Helper for accessing features in {@link android.util.TimeUtils} introduced
 * after API level 4 in a backwards compatible fashion.
 * 
 * @hide
 */
public class TimeUtils {
	/** @hide Field length that can hold 999 days of time */
	public static final int HUNDRED_DAY_FIELD_LEN = 19;

	private static final int SECONDS_PER_MINUTE = 60;
	private static final int SECONDS_PER_HOUR = 60 * 60;
	private static final int SECONDS_PER_DAY = 24 * 60 * 60;

	private static final Object sFormatSync = new Object();
	private static char[] sFormatStr = new char[HUNDRED_DAY_FIELD_LEN + 5];

	static private int accumField(int amt, int suffix, boolean always, int zeropad) {
		if (amt > 99 || (always && zeropad >= 3)) {
			return 3 + suffix;
		}
		if (amt > 9 || (always && zeropad >= 2)) {
			return 2 + suffix;
		}
		if (always || amt > 0) {
			return 1 + suffix;
		}
		return 0;
	}

	static private int printField(char[] formatStr, int amt, char suffix, int pos, boolean always, int zeropad) {
		if (always || amt > 0) {
			final int startPos = pos;
			if ((always && zeropad >= 3) || amt > 99) {
				int dig = amt / 100;
				formatStr[pos] = (char) (dig + '0');
				pos++;
				amt -= (dig * 100);
			}
			if ((always && zeropad >= 2) || amt > 9 || startPos != pos) {
				int dig = amt / 10;
				formatStr[pos] = (char) (dig + '0');
				pos++;
				amt -= (dig * 10);
			}
			formatStr[pos] = (char) (amt + '0');
			pos++;
			formatStr[pos] = suffix;
			pos++;
		}
		return pos;
	}

	private static int formatDurationLocked(long duration, int fieldLen) {
		if (sFormatStr.length < fieldLen) {
			sFormatStr = new char[fieldLen];
		}

		char[] formatStr = sFormatStr;

		if (duration == 0) {
			int pos = 0;
			fieldLen -= 1;
			while (pos < fieldLen) {
				formatStr[pos] = ' ';
			}
			formatStr[pos] = '0';
			return pos + 1;
		}

		char prefix;
		if (duration > 0) {
			prefix = '+';
		} else {
			prefix = '-';
			duration = -duration;
		}

		int millis = (int) (duration % 1000);
		int seconds = (int) Math.floor(duration / 1000);
		int days = 0, hours = 0, minutes = 0;

		if (seconds > SECONDS_PER_DAY) {
			days = seconds / SECONDS_PER_DAY;
			seconds -= days * SECONDS_PER_DAY;
		}
		if (seconds > SECONDS_PER_HOUR) {
			hours = seconds / SECONDS_PER_HOUR;
			seconds -= hours * SECONDS_PER_HOUR;
		}
		if (seconds > SECONDS_PER_MINUTE) {
			minutes = seconds / SECONDS_PER_MINUTE;
			seconds -= minutes * SECONDS_PER_MINUTE;
		}

		int pos = 0;

		if (fieldLen != 0) {
			int myLen = accumField(days, 1, false, 0);
			myLen += accumField(hours, 1, myLen > 0, 2);
			myLen += accumField(minutes, 1, myLen > 0, 2);
			myLen += accumField(seconds, 1, myLen > 0, 2);
			myLen += accumField(millis, 2, true, myLen > 0 ? 3 : 0) + 1;
			while (myLen < fieldLen) {
				formatStr[pos] = ' ';
				pos++;
				myLen++;
			}
		}

		formatStr[pos] = prefix;
		pos++;

		int start = pos;
		boolean zeropad = fieldLen != 0;
		pos = printField(formatStr, days, 'd', pos, false, 0);
		pos = printField(formatStr, hours, 'h', pos, pos != start, zeropad ? 2 : 0);
		pos = printField(formatStr, minutes, 'm', pos, pos != start, zeropad ? 2 : 0);
		pos = printField(formatStr, seconds, 's', pos, pos != start, zeropad ? 2 : 0);
		pos = printField(formatStr, millis, 'm', pos, true, (zeropad && pos != start) ? 3 : 0);
		formatStr[pos] = 's';
		return pos + 1;
	}

	/** @hide Just for debugging; not internationalized. */
	public static void formatDuration(long duration, StringBuilder builder) {
		synchronized (sFormatSync) {
			int len = formatDurationLocked(duration, 0);
			builder.append(sFormatStr, 0, len);
		}
	}

	/** @hide Just for debugging; not internationalized. */
	public static void formatDuration(long duration, PrintWriter pw, int fieldLen) {
		synchronized (sFormatSync) {
			int len = formatDurationLocked(duration, fieldLen);
			pw.print(new String(sFormatStr, 0, len));
		}
	}

	/** @hide Just for debugging; not internationalized. */
	public static void formatDuration(long duration, PrintWriter pw) {
		formatDuration(duration, pw, 0);
	}

	/** @hide Just for debugging; not internationalized. */
	public static void formatDuration(long time, long now, PrintWriter pw) {
		if (time == 0) {
			pw.print("--");
			return;
		}
		formatDuration(time - now, pw, 0);
	}
}
